Lithography.



UNITED srarps PATENT orrion.

OSCAR BUSSE,OF SAN FRANCISCO, CALIFCRNIA.

LITHOGRAPHY.

No Drawing.

To all whom it may concern:

Be it known that I, OscAn Bnssn, a citizen of the United States, and a resident of the city and county of San Francisco, State of (,alifornia. have invented new and useful Improvements in Lithography, of which the following is a specification.

This invention relates to improvements made in producing the design, picture or subject on the surface of a lithographic stone by printing thereon with a photographic negative, as a preliminary step to the Work of the-draftsman by Whom the design or picture is brought to the finished state for transferring to paper. 1

The invention has as its object the exact reproduction of the designupon as many stones as the character of the Work may call for; being especially useful in all color Work, and Where separate stones must be prepared, as Well, for the outlines and for special tints or other eflects, requiring accu rate register in printing; and being further of value in doing away With-the tedious and more or less un'oertainand ineffective work involved in transferring the design from stone to stone bythe use of chalked tracings,

according to the methods heretofore commonly' used by the draftsman in work of this character.

Heretofore, so far as I am aware, in the production of a design or picture on a lithographic stone for the guidance of the draftsman, by use of a photographic negative, the process has been confined to one-color work requiring. the use of a singlestone, and no attempt has been made to repeat the' design by sensitizing the surface of the number of stones required to produce a given piece of,

color Work, and printing on each stone by means of the same negative. But on the contrary, in the reproduction of the design on each stone the practice .of transferring by-chalked tracings has been followed. The reason for this, I findby investigation and experiment, arises fromthe objectionable qualities and effects both of the sensitizing solutions and-the fixing solution or medium employed in preparing the surface of the stone for the solar printing, and'in fixing the prints after exposure: as both the sen sitizing agents and the fixing agents heretofore employed for the purpose mentioned in lithographic work have left the surface of the stone in a more or less greasy condi- Specification of Letters Patent.

Patented Nov. 7, 1911.

Application filed February 7, 1910. Serial No. 542,434.

tion, or have produced a condition of surface that prevented it from taking the ink or crayons usedby the draftsman, and which involved also both labor and loss of time in restoring the surface to a condition'sufliciently clean for the workto such an extent that what might have been gained in sharpness and correctness of outline and accuracy of registration by reproducing the design on each separate" stone with the same photographic negative, would be offset by the expense and loss of time involved in cleaning the surfaces of the stones.

In the course of my experiments I have discovered that it is possible and practicable 'to sensitize-the surface of a lithographic stone for solar printing thereon, and after; ward to fix the picture in such manner that the surface will be in condition to take the ink and crayons of the draftsman without further treatment or manipulation, and with the most effectiveresults in sharpness, clearnessand other desirable artistic effects; The result of the improvements constituting my present invention is that its use renders possible the multiplication or reproduction of the outline, design or picture for the draftsman upon any required numbeiiof stones with the same negative, instead of transferring the same to one stone after another of the set or number by the usual method of t aoing'; thereby securing accuracy of register between the series of stones in the finished work, and simplifying as well as greatly reducing the cost of the steps or operations involved in preparing the picture for printing. I

This invention is based on the discovery 1 have made that by cxcluding' from the sensitizing agent all oily or greasy elements,

and confining the agent to a simple solution or mixture of iron and ammonium citrate, nitrate of silver and citr c acid in water,

and likewise confining the fixing agent to a' solution or mixture of desiccated sulfite of soda, powdered alum, acetic acid and'hyposulfiie of soda in water, the process of produc-ingthe design on the stone by solar printing with a negative becomes practicable in the art, and can be substituted to udvantage for the method of transferring from one stone to another bythe use of chalked tracings. i

in carrying out and practicing the said invention I repare a sensitizing solution 56 termined by the color .work at the hands of the; draftsman.

45 acid No 8, 25 per cent 50 formed of the substances. namedor" mixture of the following substances preferably taken in he proportions named Solution No. Iron' and ammonium citrate 40 grams, nitrate of silver 8 grams, citric 10 avoid streaks. After being allowed to stand several sec0nds," the stone is placed on a revolving table, or whirler, and dried. It is better, usually, to coat and prepare the surface of a stone one day, to be used the next dayn 1h '1- t f Upon the sensitized surface the design or subject for the picture is printed by exposure to sun-light under the negative; the length of-exposure bein regulated and de- Tf f the surface, which shouldbe a deep brown, and the stone should be removed from the light and subjected tothe fixin process when that condition is reached, nderlonger exposure the color.

of the surface will'change toaxyellow, hue,

which is destructive: of subsequent good The same condition is liable to be produced, also, if thecoating of sensitizing solution be applied to the surface too' thin-' After the proper length of exposure, the stone is to be removed from the sun-lightand placed in a fixing pan of any well known kind, and the surface washed by flowing water over it, care being. taken to cover the surface thoroughly- -by allowing the stream to run over it. The surface thus treated being ready for fixing the'sun print, the water is,

run off, and" the ,stone is subjected to the 40 second-step of the process in which the so lution composed 'offthe following mixtures or solutions is.employed:.'

SoZutz'onA.-'- 'esiccated sulfite of soda 7.25

grams, powdered-alum 15.5 grams, acetic meters, water 78 cu-.5cent1meters.

Solution B.Hypo-sul fite of soda 25d grams, water 1000 cu. centimeters.

"Each of the above solutions is preferably 'n about the proportions given. They are i B is added to solution A, producing solucurateregistration,

ure, 46 cu. centi ixed sepa, rately until thesubstances have become thoroughly dissolved, after which solution tion 2. To produce the fixing solution a quantity of solution 2- is diluted with water,

, crayons.

With the solutions properly compounded and ready, the entire process of solar printing, fixing and drying should not consume more than thirty minutes. Ordinarily, the exposure to the sun-light should be about three minutes duration.

The whole number of stones employed in a given piece-of colorwork prepared and treated according to this invention will have the design or picture produced on their surfaces in exact correspondence to insure acand with all the characteristics and details reproduced in a more complete manner than it is possible to transfer and produce on the stone by the use of chalked tracings.

' I claiinz- That improvement in preparing the design or picture in multiple on lithographic stones for the production of -the same in colors which consists in sensitizing the surfaces of the stones by coating the same with a preparation of iron and ammonium citrate, nitrate of' silver, and citric acid in water in about the proportions hereinbefore. given, then drying the surface, then exposing said sensitizin surface to sunlight under a negative of a design or picture, then washing the surface andfixing the print by immersing the surface in' a solution of desiccated sul- 'fite of soda, powdered alum, acetic acid, and

hypo-sulfite of soda in water, in, about the proportions hereinbefore given, and then' drying the surface, thereby leaving. the surface incondition to take the ink and crayo'ns of the draftsman without further treatment or manipulation, substantially as set forth.

' OSCAR BUSSE.

Witnesses v E; E. OsBoRN, M.: REGNEB.

. v A 4 'I: v Oopies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents,

Washington, ,0." 

